Nketiah passed Alan Shearer and Francis Jeffers to become England U21’s all-time leading goalscorer this week.
The 21-year-old has made 43 appearances for Arsenal’s first-team and can develop into ‘one hell of a player’, according to Cascarino.
‘Although Leeds United did not benefit particularly from Nketiah’s loan spell there, it did the player himself the world of good,’ he told The Times.
‘It helped him reach a level of fitness that is very useful to Arteta, who has shown he believes in the player.
‘Nketiah loves to get on the shoulders of defenders and turn them before darting in behind with his blistering pace.
‘He is agile with quick feet, much like his hero Ian Wright, which denies defenders the time to settle.
‘He makes clever runs, taking defenders where they don’t want to go.
‘A lot of young players coming through nowadays are more capable on their weaker foot than their predecessors were, and Nketiah ticks that box.
Former Republic of Ireland striker Cascarino added: ‘There is still more to come from Nketiah too.
‘If he develops greater confidence in front of goal then you will have one hell of a player.
‘He needs to improve his goalscoring with Arsenal, but his exploits with England show he is capable of that.’
After becoming England U21s record goalscorer, Nketiah said: ‘It is an amazing feeling.
‘It is nice to get the three points but to beat the record is a dream come true and a proud moment for me and my family. There are still games left to add to that.’